Carbon cycles through Earth, its inhabitants, and its atmosphere on a regular basis, but not much research has been done on that process and qualifying it — until now.

In a recent study of a river system extending from the Peruvian Andes to the Amazon floodplains, Rice University’s Mark Torres and collaborators from five institutions proved that that high rates of carbon breakdown persist from mountaintop to floodplain.

“The purpose of this research was to quantify the rate at which Earth naturally releases carbon dioxide into the atmosphere and find out whether this process varies across different geographic locations,” Torres says in a news release.

Torres published his findings in a study published in PNAS, explaining how they used rhenium — a silvery-gray, heavy transition metal — as a proxy for carbon. The research into the Earth’s natural, pre-anthropogenic carbon cycle stands to benefit humanity by providing valuable insight to current climate challenges.

“This research used a newly-developed technique pioneered by Robert Hilton and Mathieu Dellinger that relies on a trace element — rhenium — that’s incorporated in fossil organic matter,” Torres says. “As plankton die and sink to the bottom of the ocean, that dead carbon becomes chemically reactive in a way that adds rhenium to it.”

The research was done in the Rio Madre de Dios basin and supported by funding from a European Research Council Starting Grant, the European Union COFUND/Durham Junior Research Fellowship, and the National Science Foundation.

“I’m very excited about this tool,” Torres said. “Rice students have deployed this same method in our lab here, so now we can make this kind of measurement and apply it at other sites. In fact, as part of current research funded by the National Science Foundation, we are applying this technique in Southern California to learn how tectonics and climate influence the breakdown of fossil carbon.”

Torres also received a three-year grant from the Department of Energy to study soil for carbon storage earlier this year.